(a) Field of the Invention PA1 (b) Description of the Prior Art
The present invention relates to a phenolic resin composition and an epoxy-cured product in which the composition is used as a curing agent. More specifically, the present invention relates to a phenolic resin composition which is useful as, for example, an intermediate for preparing epoxy resins used in, for instance, molding compounds for semiconductor devices, preparing laminate materials and paints and varnishes, or a curing agent for such epoxy resins, has a low viscosity and permits epoxy-cured products formed by curing an epoxy resin to be improved in heat resistance and resistance to moisture as well as an epoxy-cured product in which the composition is used as a curing agent.
Phenolic compounds have been used as intermediates for preparing epoxy resins or used as curing agents for epoxy resins or the like in order to prepare heat resistant composite materials and heat resistant adhesives comprising such epoxy resins, diversity of such epoxy resins in their applications has recently become increasingly high and accordingly, they are industrially important materials. For this reason, it has been desired to impart more improved quality to epoxy-cured products.
Japanese Un-examined Patent Publication No. Hei 1-95124 proposes, as a curing agent for epoxy resins, a phenol aralkyl resin having a low molecular weight and a low viscosity. The phenol aralkyl resin has a low viscosity and is excellent in flow properties, but has an extremely low molecular weight. For this reason, it has a high content of binuclear components and causes brittle epoxy-cured products formed by curing an epoxy resin with the phenol aralkyl resin as a curing agent.
With the recent marked advancement of the electric electronic technology, there has been desired the development of a resin which is used in such a field and can ensure excellent quality even when it is used in a small amount. For instance, molding compounds for IC's and laminate materials require the use of .resins having a lower viscosity and accordingly, it is important to decrease the viscosity thereof while maintaining the desired properties such as heat resistance and resistance to cracking.